Node.js

Question 1

What is Node.js?

Answer 1

Node.js is a program that allows JavaScript to be run outside of a web browser.

Question 2

What can Node.js be used for?

Answer 2

It is commonly used to build back ends for Web applications, command-line programs, or any kind of automation that developers wish to perform.

Question 3

What is a REPL?

Answer 3

A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise.

Takes input, evaluates it, prints output, and goes back to beginning like the console.

Question 4

When was Node.js created?

Answer 4

2009

Question 5

What back end languages have you heard of?

Answer 5

Ruby, Python, PHP, C++, JavaScript, C, java, C#

Question 6

What is a computer process?

Answer 6

A program that is running on your computer. This can be anything from a small background task, such as a spell-checker or system events handler to a full-blown application like Internet Explorer or Microsoft Word. All processes are composed of one or more threads.

Question 7

Roughly how many computer processes are running on your host operating system (Task Manager or Activity Monitor)?

Answer 7

A lot.

540 on mine.

Question 8

What is the process object in a Node.js program?

Answer 8

The process object is the global object in Node. It can be accessed from anywhere; it is an instance of EventEmitter. Each Node.js has a set of built-in functionality, accessible through the global process object.

Question 9

How do you access the process object in a Node.js program?

Answer 9

It is global so you can just type it.

Question 10

What is the data type of process.argv in Node.js?

Answer 10

Array of strings.

Question 11

What is a JavaScript module?

Answer 11

In JavaScript, a “module” is a single .js file.

Question 12

What values are passed into a Node.js module’s local scope?

Answer 12

\_\_dirname
\_\_filename
exports
module
require( )

Question 13

Give two examples of truly global variables in a Node.js program.

Answer 13

process and console.

Question 14

What is the purpose of module.exports in a Node.js module?

Answer 14

To export some code to another Node.js module.

Question 15

How do you import functionality into a Node.js module from another Node.js module?

Answer 15

const variable = require(file-path)

Ex:
const addFunction = require('./add');

Question 16

What is the JavaScript Event Loop?

Answer 16

The JavaScript event loop is basically an endless loop, which keeps on checking whether there is something to be executed in the call stack. If the call stack is empty it checks the Event Queue, whether there is something to move to the call stack.

Question 17

What is different between “blocking” and “non-blocking” with respect to how code is executed?

Answer 17

“blocking”: waits for execution to complete before moving to the next call-stack. Synchronous

“non-blocking”: does not wait for execution to complete before moving the the next call-stack. Asynchronous

Question 18

What is a directory?

Answer 18

Folder/collection for files.

Question 19

What is a relative file path?

Answer 19

The path with reference to current directory.

Question 20

What is an absolute file path?

Answer 20

The path with reference to the root directory.

Question 21

What module does Node.js include for manipulating the file system?

Answer 21

fs

Question 22

What method is available in the Node.js fs module for writing data to a file?

Answer 22

fs.writeFile

Question 23

Are file operations using the fs module synchronous or asynchronous?

Answer 23

Both synchronous and asynchronous

readfile and readfile sync

Question 24

How are ES Modules different from CommonJS modules?

Answer 24

Their syntax is even more compact than CommonJS’s.
Their structure can be statically analyzed (for static checking, optimization, etc.).
Their support for cyclic dependencies is better than CommonJS’s.

Use import instead of require
Use export instead of module.exports